System.Xml.XmlTextReaderImpl.AddAttribute C# (CSharp) Method

        private NodeData AddAttribute(string localName, string prefix, string nameWPrefix)
        {
            NodeData newAttr = AddNode(_index + _attrCount + 1, _index + 1);

            // set attribute name
            newAttr.SetNamedNode(XmlNodeType.Attribute, localName, prefix, nameWPrefix);

            // pre-check attribute for duplicate: hash by first local name char
            int attrHash = 1 << (localName[0] & 0x1F);
            if ((_attrHashtable & attrHash) == 0)
            {
                _attrHashtable |= attrHash;
            }
            else
            {
                // there are probably 2 attributes beginning with the same letter -> check all previous 
                // attributes
                if (_attrDuplWalkCount < MaxAttrDuplWalkCount)
                {
                    _attrDuplWalkCount++;
                    for (int i = _index + 1; i < _index + _attrCount + 1; i++)
                    {
                        NodeData attr = _nodes[i];
                        Debug.Assert(attr.type == XmlNodeType.Attribute);
                        if (Ref.Equal(attr.localName, newAttr.localName))
                        {
                            _attrDuplWalkCount = MaxAttrDuplWalkCount;
                            break;
                        }
                    }
                }
            }

            _attrCount++;
            return newAttr;
        }